Abstract:

A power supply ECU executes a program including the steps of: transmitting
an auto-P request signal if a power switch is in the short pressed state
and if a speed V of a vehicle is lower than a predetermined speed
α; starting a timer; turning off an IG relay and an ACC relay if a
P position signal and an auto-P completion signal are received before a
predetermined time period T has elapsed; and maintaining the IG relay and
the ACC relay in the ON state if the predetermined time period has
elapsed and if the speed V of the vehicle is higher than or equal to the
predetermined speed α.

Claims:

1.-24. (canceled)

25. A control device for a vehicle on which an internal combustion engine
and a transmission provided with a parking lock mechanism are mounted,
said parking lock mechanism switching between limitation of rotation of a
driving wheel of said vehicle and release of the limitation by using a
gear mechanism driven by an actuator based on an electrical signal
corresponding to a state of an operation member, said actuator being
driven by receiving electric power feed from a power supply, said control
device comprising:a speed detecting unit for detecting a speed of said
vehicle;an actuation state detecting unit for detecting a physical amount
related to an actuation state of said parking lock mechanism ; anda
control unit for receiving outputs from said actuation state detecting
unit and said speed detecting unit,said control unitdetermining whether
or not an instruction to stop said internal combustion engine has been
received, based on said electrical signal,controlling said actuator such
that the rotation of said driving wheel is limited by said parking lock
mechanism, when receiving the instruction to stop said internal
combustion engine,determining whether or not the rotation of said driving
wheel is limited based on said physical amount detected, when receiving
the instruction to stop said internal combustion engine,maintaining said
internal combustion engine in an actuated state, when determining that
the rotation of said driving wheel is not limited by said parking lock
mechanism and when said speed of the vehicle is higher than or equal to a
predetermined speed,stopping said internal combustion engine and
maintaining the electric power feed from said power supply to said
actuator, when determining that the rotation of said driving wheel is not
limited by said parking lock mechanism and when said speed of the vehicle
is lower than said predetermined speed, andstopping said internal
combustion engine and stopping the electric power feed from said power
supply to said actuator, when determining that the rotation of said
driving wheel is limited by said parking lock mechanism.

26. The control device for a vehicle according to claim 25, whereinsaid
parking lock mechanism includes a gear provided at a shaft coupled to
said driving wheel, and a member for limiting rotation of said gear or
releasing limiting rotation of said gear,said actuation state detecting
unit detects a location of said member, andsaid control unit determines
that the rotation of said driving wheel is not limited, when said
location detected is not a location where the rotation of said gear is
limited.

27. The control device for a vehicle according to claim 25, whereinsaid
actuator is a rotating electric machine driven by receiving the electric
power feed from said power supply,said actuation state detecting unit
detects the electric power of said power supply, andsaid control unit
determines that the rotation of said driving wheel is not limited, when
said electric power detected is not electric power that allows driving of
said actuator.

28. The control device for a vehicle according to claim 25, further
comprisinga notifying unit for notifying an occupant of said vehicle that
said internal combustion engine is maintained in the actuated state, when
it is determined that the rotation of said driving wheel is not limited.

29. The control device for a vehicle according to claim 25, whereinsaid
control unitdetermines whether or not an instruction to forcibly stop
said internal combustion engine has been received, based on said
electrical signal, andstops said internal combustion engine when
receiving the instruction to forcibly stop said internal combustion
engine.

30. The control device for a vehicle according to claim 25, whereinthe
state of said operation member is a state based on a time period during
which operation of said operation member continues.

31. The control device for a vehicle according to claim 25, further
comprisinga traveling state detecting unit for detecting a traveling
state of said vehicle, whereinsaid control unitreceives an output from
said traveling state detecting unit,determines whether or not said
vehicle is at a standstill, based on said traveling state detected,
andstops said internal combustion engine when determining that the
rotation of said driving wheel is not limited and said vehicle is at a
standstill.

32. The control device for a vehicle according to claim 31, whereinsaid
traveling state detecting unit detects a speed of said vehicle, andsaid
control unit determines that said vehicle is at a standstill, when said
speed of the vehicle detected is lower than a predetermined speed after a
predetermined time period has elapsed from a point in time when the
instruction to stop said internal combustion engine was received.

33. The control device for a vehicle according to claim 25, whereinsaid
parking lock mechanism includesa parking lock gear provided at a shaft
coupled to said driving wheel and having a gear tooth along a direction
of rotation,a parking lock pole supported by a case of said transmission
and having a protrusion that meshes with said gear tooth, anda limiting
unit for limiting the rotation of said driving wheel by meshing said gear
tooth and said protrusion of said parking lock pole in accordance with
driving of said actuator.

34. The control device for a vehicle according to claims 25, whereina
brake device for producing braking force by using a negative pressure
generated as a result of actuation of said internal combustion engine
when said internal combustion engine is actuated is mounted on said
vehicle.

35. A method for controlling a vehicle on which an internal combustion
engine and a transmission provided with a parking lock mechanism are
mounted, said parking lock mechanism switching between limitation of
rotation of a driving wheel of said vehicle and release of the limitation
by using a gear mechanism driven by an actuator based on an electrical
signal corresponding to a state of an operation member, said actuator
being driven by receiving electric power feed from a power supply, said
method for controlling a vehicle comprising the steps of:detecting a
speed of said vehicle;detecting a physical amount related to an actuation
state of said parking lock mechanism;determining whether or not an
instruction to stop said internal combustion engine has been received,
based on said electrical signal;controlling said actuator such that the
rotation of said driving wheel is limited by said parking lock mechanism,
when the instruction to stop said internal combustion engine has been
received;determining whether or not the rotation of said driving wheel is
limited based on said physical amount detected, when the instruction to
stop said internal combustion engine has been received;maintaining said
internal combustion engine in an actuated state, when it is determined
that the rotation of said driving wheel is not limited by said parking
lock mechanism and when said speed of the vehicle is higher than or equal
to a predetermined speed;stopping said internal combustion engine and
maintaining the electric power feed from said power supply to said
actuator when it is determined that the rotation of said driving wheel is
not limited by said parking lock mechanism and when said speed of the
vehicle is lower than said predetermined speed; andstopping said internal
combustion engine and stopping the electric power feed from said power
supply to said actuator, when it is determined that the rotation of said
driving wheel is limited by said parking lock mechanism.

36. The method for controlling a vehicle according to claim 35,
whereinsaid parking lock mechanism includes a gear provided at a shaft
coupled to said driving wheel, and a member for limiting rotation of said
gear or releasing the limitation,in said step of detecting a physical
amount related to an actuation state of said parking lock mechanism, a
location of said member is detected, andin said step of determining
whether or not the rotation of said driving wheel is limited, it is
determined that the rotation of said driving wheel is not limited, when
said location detected is not a location where the rotation of said gear
is limited.

37. The method for controlling a vehicle according to claim 35,
whereinsaid actuator is a rotating electric machine driven by receiving
the electric power feed from said power supply,in said step of detecting
a physical amount related to an actuation state of said parking lock
mechanism, the electric power of said power supply is detected, andin
said step of determining whether or not the rotation of said driving
wheel is limited, it is determined that the rotation of said driving
wheel is not limited, when said electric power detected is not electric
power that allows driving of said actuator.

38. The method for controlling a vehicle according to claim 35, further
comprising the step ofnotifying an occupant of said vehicle that said
internal combustion engine is maintained in the actuated state, when it
is determined that the rotation of said driving wheel is not limited.

39. The method for controlling a vehicle according to claim 35, further
comprising the steps of:determining whether or not an instruction to
forcibly stop said internal combustion engine has been received, based on
said electrical signal, andstopping said internal combustion engine when
the instruction to forcibly stop said internal combustion engine has been
received.

40. The method for controlling a vehicle according to claim 35, whereinthe
state of said operation member is a state based on a time period during
which operation of said operation member continues.

41. The method for controlling a vehicle according to claim 35, further
comprising the steps of:detecting a traveling state of said
vehicle;determining whether or not said vehicle is at a standstill, based
on said traveling state detected; andstopping said internal combustion
engine when it is determined that the rotation of said driving wheel is
not limited and said vehicle is at a standstill.

42. The method for controlling a vehicle according to claim 41, whereinin
said step of detecting a traveling state of said vehicle, a speed of said
vehicle is detected, andin said step of determining whether or not said
vehicle is at a standstill, it is determined that said vehicle is at a
standstill, when said speed of the vehicle detected is lower than a
predetermined speed after a predetermined time period has elapsed from a
point in time when the instruction to stop said internal combustion
engine was received.

43. The method for controlling a vehicle according to claim 25,
whereinsaid parking lock mechanism includesa parking lock gear provided
at a shaft coupled to said driving wheel and having a gear tooth along a
direction of rotation,a parking lock pole supported by a case of said
transmission and having a protrusion that meshes with said gear tooth,
anda limiting unit for limiting the rotation of said driving wheel by
meshing said gear tooth and said protrusion of said parking lock pole in
accordance with driving of said actuator.

44. The method for controlling a vehicle according to claims 25, whereina
brake device for producing braking force by using a negative pressure
generated as a result of actuation of said internal combustion engine
when said internal combustion engine is actuated is mounted on said
vehicle.

Description:

TECHNICAL FIELD

[0001]The present invention relates to a control device for a vehicle on
which an internal combustion engine and a transmission provided with a
parking lock mechanism are mounted, and in particular, to the stop
control of the internal combustion engine in accordance with an actuation
state of the parking lock mechanism.

BACKGROUND ART

[0002]Conventionally, an automatic transmission mounted on a vehicle is
provided with a parking lock mechanism that limits the rotation of an
output shaft of the automatic transmission when a shift position is
switched to a parking position. The parking lock mechanism includes a
parking lock gear provided on the output shaft side and having a
plurality of gear teeth, and a parking lock pole having a protrusion that
can mesh with the gear teeth. When the shift position is switched to the
parking position, the protrusion meshes with the gear teeth, thereby
limiting the rotation of the output shaft.

[0003]In a shift switching mechanism that switches the shift position
(that will also be referred to as a range in the following description)
of an automatic transmission by an actuator in accordance with the
driver's operation of a shift lever, a mechanism including a motor (e.g.,
a DC motor) as a power source for switching the shift position has been
known.

[0004]According to the shift switching mechanism as described above, there
is no need to mechanically connect the shift lever and the shift
switching mechanism as in a common switching mechanism that directly
switches the shift position of the automatic transmission using operation
force applied to the shift lever by a driver. Therefore, there is no
limitation in layout when these components are mounted on a vehicle, and
thus, the flexibility in design can be enhanced. In addition, there is an
advantage that mounting on the vehicle can be readily carried out.

[0005]As such shift switching mechanism, Japanese Patent Laying-Open No.
4-69450 (Patent Document 1), for example, discloses a transmission
apparatus by electronic control whose operability is improved by
controlling a shift actuator in response to operation of an ignition
switch or controlling a brake actuator in response to switching of the
shift position. This transmission apparatus by electronic control
includes: a select switch; calculating means for outputting a control
signal in response to an input signal from the select switch; and a shift
actuator for switching a shift position of a shift gear in response to
the control signal from the calculating means, the calculating means
including a shift control unit for controlling the shift actuator to
switch the shift position to a parking position in response to an
ignition switch.

[0006]According to the transmission apparatus by electronic control
disclosed in the above publication, movement of the vehicle, which is not
intended by the driver, resulting from the switching of the shift
position can be prevented before it occurs, without worsening the
operability. [0007]Patent Document 1: Japanese Patent Laying-Open No.
4-69450

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

[0008]When the parking lock mechanism is actuated together with stop of an
engine, it takes time to complete actuation of the parking lock
mechanism. Therefore, if actuation of the parking lock mechanism is not
completed after the engine stops, or if the parking lock mechanism is not
actuated for some reasons, the location of the vehicle is fixed
dependently on braking force of a brake device. Since gravity is applied
to the vehicle on a road surface having an inclination such as an uphill
road, in particular, it is required to limit the movement using the
braking force of the brake device of the vehicle until actuation of the
parking lock mechanism is completed.

[0009]In the brake device of the vehicle, however, the operation force
applied to the brake pedal by the driver is boosted by using the negative
pressure in an intake pipe in the case of a vehicle having a gasoline
engine mounted thereon, or the negative pressure by a negative pressure
pump actuated by the motive power of the engine in the case of a vehicle
having a diesel engine mounted thereon. Therefore, if the engine stops
before the parking lock mechanism is actuated, the sufficient brake
performance cannot be ensured in some cases. Thus, the vehicle moves
contrary to the driver's intention.

[0010]The present invention has been made to solve the above-described
problems, and an object thereof is to provide a control device for a
vehicle and a method for controlling a vehicle that suppress the movement
of the vehicle contrary to the driver's intention.

Means for Solving the Problems

[0011]A control device for a vehicle according to an aspect of the present
invention is a control device for a vehicle on which an internal
combustion engine and a transmission provided with a parking lock
mechanism are mounted. The parking lock mechanism switches between
limitation of rotation of a shaft coupled to a driving wheel of the
vehicle and release of the limitation, by using a gear mechanism driven
by an actuator based on an electrical signal corresponding to a state of
an operation member. The control device includes: a detecting unit for
detecting a physical amount related to an actuation state of the parking
lock mechanism; and a control unit for receiving an output from the
detecting unit. The control unit determines whether or not an instruction
to stop the internal combustion engine has been received, based on the
electrical signal, determines whether or not the rotation of the shaft is
limited based on the physical amount detected, when receiving the
instruction to stop the internal combustion engine, maintains the
internal combustion engine in an actuated state, when determining that
the rotation of the shaft is not limited, and stops the internal
combustion engine, when determining that the rotation of the shaft is
limited.

[0012]According to the first invention, even when the instruction to stop
the internal combustion engine is received, the internal combustion
engine is maintained in the actuated state if it is determined that the
rotation of the shaft is not limited. This allows suppression of stop of
the internal combustion engine before actuation of the parking lock
mechanism is completed. Therefore, degradation in brake performance due
to the stop of the internal combustion engine can be suppressed. For
example, even when the vehicle moves during parking of the vehicle on a
road surface having an inclination and during actuation of the parking
lock mechanism after the instruction to stop the internal combustion
engine is received, the location of the vehicle can be fixed by the
driver's operation of a brake, to suppress the movement of the vehicle
which is not intended by the driver. In addition, when actuation of the
parking lock mechanism is completed, the movement of the vehicle can be
adapted to the driver's intention by stopping the internal combustion
engine. Accordingly, there can be provided a control device for a vehicle
and a method for controlling a vehicle that suppress the movement of the
vehicle contrary to the driver's intention.

[0013]Preferably, the detecting unit detects a speed of the vehicle. The
control unit determines that the rotation of the shaft is not limited,
when the speed of the vehicle detected is higher than or equal to a
predetermined speed.

[0014]According to the present invention, when the speed of the vehicle
detected is higher than or equal to the predetermined speed, it can be
determined that the rotation of the shaft is not limited, that is,
actuation of the parking lock mechanism is not completed.

[0015]More preferably, the parking lock mechanism includes a gear provided
at the shaft, and a member for limiting rotation of the gear or releasing
limiting rotation of the gear. The detecting unit detects a location of
the member. The control unit determines that the rotation of the shaft is
not limited, when the location detected is not a location where the
rotation of the gear is limited.

[0016]According to the present invention, when the location of the member
for limiting the rotation of the gear or releasing limiting the rotation
of the gear is not the location where the rotation of the gear is
limited, it can be determined that the rotation of the shaft is not
limited, that is, actuation of the parking lock mechanism is not
completed.

[0017]More preferably, the actuator is a rotating electric machine driven
by receiving electric power feed from a power supply. The detecting unit
detects electric power of the power supply. The control unit determines
that the rotation of the shaft is not limited, when the electric power
detected is not electric power that allows driving of the actuator.

[0018]According to the present invention, when the electric power detected
is not the electric power that allows driving of the actuator, the
parking lock mechanism cannot be actuated, and thus, it can be determined
that the rotation of the shaft is not limited.

[0019]More preferably, the control unit starts up the internal combustion
engine at a standstill.

[0020]According to the present invention, when the internal combustion
engine is at a standstill, degradation in performance of the brake using
the negative pressure based on actuation of the internal combustion
engine can be suppressed by starting up the internal combustion engine.

[0021]More preferably, the control device further includes a notifying
unit for notifying an occupant of the vehicle that the internal
combustion engine is maintained in the actuated state, when it is
determined that the rotation of the shaft is not limited.

[0022]According to the present invention, by notifying the occupant of the
vehicle that the internal combustion engine is maintained in the actuated
state, the occupant of the vehicle can recognize that the internal
combustion engine cannot be stopped because actuation of the parking lock
mechanism is not completed, and can be encouraged to actuate a brake
device.

[0023]More preferably, the control unit determines whether or not an
instruction to forcibly stop the internal combustion engine has been
received, based on the electrical signal, and stops the internal
combustion engine when receiving the instruction to forcibly stop the
internal combustion engine.

[0024]According to the present invention, the internal combustion engine
can be forcibly stopped in accordance with the driver's intention.

[0025]More preferably, the state of the operation member is a state based
on a time period during which operation of the operation member
continues.

[0026]According to the present invention, by changing the time period
during which operation of the operation member continues, the driver can
select the manner of stop of the internal combustion engine that is
adapted to the driver's intention, such as forced stop of the internal
combustion engine, stop of the internal combustion engine after actuation
of the parking lock mechanism is completed, or the like.

[0027]More preferably, the control device further includes a state
detecting unit for detecting a traveling state of the vehicle. The
control unit receives an output from the state detecting unit, determines
whether or not the vehicle is at a standstill, based on the traveling
state detected, and stops the internal combustion engine when determining
that the rotation of the shaft is not limited and the vehicle is at a
standstill.

[0028]According to the present invention, when it is determined that the
vehicle is at a standstill, the location of the vehicle is in a fixed
state. Therefore, the movement of the vehicle can be adapted to the
driver's intention by stopping the internal combustion engine regardless
of the actuation state of the parking lock mechanism.

[0029]More preferably, the state detecting unit detects a speed of the
vehicle. The control unit determines that the vehicle is at a standstill,
when the speed of the vehicle detected is lower than a predetermined
speed after a predetermined time period has elapsed from a point in time
at the earliest when the instruction to stop the internal combustion
engine was received.

[0030]According to the present invention, when the speed of the vehicle is
lower than the predetermined speed after the predetermined time period
has elapsed from the point in time at the earliest when the instruction
to stop the internal combustion engine was received, the location of the
vehicle is in the fixed state. Therefore, the movement of the vehicle can
be adapted to the driver's intention by stopping the internal combustion
engine regardless of the actuation state of the parking lock mechanism.

[0031]More preferably, the parking lock mechanism includes a parking lock
gear provided at the shaft and having a gear tooth along a direction of
rotation, a parking lock pole supported by a case of the transmission and
having a protrusion that meshes with the gear tooth, and a limiting unit
for limiting the rotation of the shaft by meshing the gear tooth and the
protrusion of the parking lock pole in accordance with driving of the
actuator.

[0032]According to the present invention, when it is determined that the
rotation of the shaft is not limited based on the physical amount related
to the actuation state of the parking lock mechanism, the internal
combustion engine is maintained in the actuated state and degradation in
brake performance can be suppressed.

[0033]More preferably, a brake device for producing braking force by using
a negative pressure generated as a result of actuation of the internal
combustion engine is mounted on the vehicle.

[0034]According to the present invention, when it is determined that the
rotation of the shaft is not limited based on the physical amount related
to the actuation state of the parking lock mechanism, the internal
combustion engine is maintained in the actuated state, and degradation in
performance of the brake using the negative pressure generated as a
result of actuation of the internal combustion engine can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 illustrates a configuration of a vehicle on which a control
device for the vehicle according to the present embodiment is mounted.

[0036]FIG. 2 illustrates a configuration of a shift switching mechanism in
FIG. 1.

[0037]FIG. 3 illustrates a configuration of a parking lock mechanism.

[0038]FIG. 4 is a functional block diagram of a power supply ECU and an
SBW-ECU.

[0039]FIG. 5 is a flowchart illustrating a control structure of a program
running on the power supply ECU.

[0040]FIG. 6 is a flowchart illustrating a control structure of a program
running on the SBW-ECU.

[0042]Embodiments of the present invention will be described hereinafter
with reference to the drawings. In the following description, the same
components are denoted with the same reference characters. Their names
and functions are also the same. Thus, detailed description on them will
not be repeated.

[0043]FIG. 1 illustrates a configuration of a shift control system 10
including a control device for a vehicle according to the present
embodiment. Shift control system 10 according to the present embodiment
is used to switch the shift position of the vehicle. Shift control system
10 includes a shift operation unit 20, an actuator unit 40, a shift
switching mechanism 48, an automatic transmission 30, an engine 32, an
SBW (Shift By Wire)-ECU (Electronic Control Unit) 50, an ECT (Electronic
Controlled Automatic Transmission)-ECU 52, an EFI (Electronic Fuel
Injection)-ECU 54, a VSC (Vehicle Stability Control)-ECU 56, a meter 58,
a power supply ECU 60, a power switch 62, a vehicle speed sensor 64, a
power supply relay 66, and a brake device 72. The control device for the
vehicle according to the present embodiment is implemented by power
supply ECU 60.

[0044]SBW-ECU 50, ECT-ECU 52, EFI-ECU 54, VSC-ECU 56, meter 58, and power
supply ECU 60 are mutually connected by a communication line (bus) 402,
and data transfer between the vehicle-mounted equipment is implemented by
the CAN (Controller Area Network) communication.

[0045]Shift operation unit 20 is configured by a P switch 22 and a shift
switch 24. Actuator unit 40 is configured by an actuator 42, an output
shaft sensor 44 and an encoder 46. Power supply relay 66 includes an IG
relay 68 and an ACC relay 70.

[0046]In the configuration as described above, shift control system 10
functions as a shift by wire system that switches the shift position by
electric control. Specifically, shift switching mechanism 48 is driven by
actuator 42 to switch the shift position.

[0047]P switch 22 is for switching the shift position between the parking
position (that will be described as "P position" hereinafter) and the
shift position other than the parking position (that will be described as
"non-P position" hereinafter), and includes an indicator for indicating
the state of the switch to the driver and an input unit for accepting an
instruction from the driver (both are not shown). The driver inputs an
instruction to place the shift position in the P position, through the
input unit. The input unit may be a momentary switch. A P command signal
indicating the instruction from the driver that is accepted by the input
unit is transmitted to SBW-ECU 50. It is noted that, in the present
embodiment, SBW-ECU 50 switches the shift position from the non-P
position to the P position in response to a request from power supply ECU
60, except for such P switch 22.

[0048]In order to switch the shift position between the P position and the
non-P position, SBW-ECU 50 controls the operation of actuator 42 that
drives shift switching mechanism 48, and presents the state of the
current shift position to an indicator (not shown) of meter 58. When the
driver presses the input unit of P switch 22 or when SBW-ECU 50 receives
an auto-P request signal from power supply ECU 60, with the shift
position in the non-P position, SBW-ECU 50 switches the shift position to
the P position and presents to the indicator that the current shift
position is in the P position. It is noted that, when the speed of the
vehicle is higher than or equal to a predetermined speed α, SBW-ECU
50 does not switch the shift position to the P position.

[0049]Actuator 42 is configured by a switched reluctance motor (that will
be described as "SR motor" hereinafter), and receives an actuator control
signal from SBW-ECU 50 and drives shift switching mechanism 48.

[0050]Encoder 46 rotates integrally with actuator 42 and detects the
situation of the rotation of the SR motor. Encoder 46 in the present
embodiment is a rotary encoder that outputs signals of an A phase, a B
phase and a Z phase. SBW-ECU 50 grasps the situation of the rotation of
the SR motor by obtaining the signal output from encoder 46, and controls
conduction for driving the SR motor.

[0051]Shift switch 24 is for switching the shift position to the position
such as a forward drive position (that will be described as "D position"
hereinafter), a rearward drive position (that will be described as "R
position" hereinafter) and a neutral position (that will be described as
"N position" hereinafter), or for clearing the selection of the P
position when the shift position is in the P position. A switching signal
(that will also be referred to as a shift signal hereinafter) indicating
an instruction from the driver that is accepted by shift switch 24 is
transmitted to SBW-ECU 50. In other words, shift switch 24 transmits, to
SBW-ECU 50, the shift signal indicating the shift position corresponding
to the location of an operation member (e.g., shift lever) operated by
the driver. SBW-ECU 50 exercises control for switching the shift position
in automatic transmission 30 by actuator 42 based on the shift signal
indicating the instruction from the driver, and in addition, presents the
state of the current shift position to meter 58.

[0052]More specifically, when the shift position corresponding to the
location of the shift lever based on the shift signal received from shift
switch 24 is different from the shift position based on the rotational
position and the amount of rotation of actuator 42 detected by output
shaft sensor 44, encoder 46 and the like, SBW-ECU 50 drives actuator 42
to switch to the shift position corresponding to the location of the
shift lever. In the present embodiment, when the switched shift position
is in the P position, SBW-ECU 50 transmits, to power supply ECU 60, a P
position signal indicating that the shift position has been switched to
the P position. In addition, when the switched shift position is in the
non-P position, SBW-ECU 50 transmits, to power supply ECU 60, a non-P
position signal indicating that the shift position has been switched to
the non-P position.

[0053]Although automatic transmission 30 is described as a gear type
automatic transmission in the present embodiment, automatic transmission
30 is not particularly limited thereto, but may be, for example, a
continuously variable automatic transmission.

[0054]Automatic transmission 30 is provided with a hydraulic circuit
including various valves such as a manual valve, for example, and a
change in the hydraulic pressure in the hydraulic circuit causes a change
in the shift position and the motive power transfer state. More
specifically, automatic transmission 30 is provided with a planetary gear
mechanism as well as a frictional engagement element such as a brake
element and a clutch element that changes the manner of rotation of each
rotation element (i.e., a sun gear, a carrier, a ring gear and the like)
of the planetary gear mechanism.

[0055]A spool valve is provided in the manual valve to slide therein. When
the spool valve is moved to the location corresponding to each shift
position, the hydraulic pressure in the hydraulic circuit changes in
accordance with the location to which the spool valve is moved.

[0056]At this time, engagement force in the frictional engagement element
changes in accordance with the change in the hydraulic pressure in the
hydraulic circuit, and automatic transmission 30 changes to the state
corresponding to each shift position. In other words, the state of motive
power transfer from engine 32 to a driving wheel in automatic
transmission 30 (e.g., any state of forward movement, rearward movement
and motive power interruption, or a gear ratio) changes. The engagement
force in this frictional engagement element is controlled by ECT-ECU 52
by using various solenoid valves provided at the hydraulic circuit.

[0057]Shift switching mechanism 48 includes a shaft coupled to actuator
42. The shaft is provided with a detent plate that will be described
later.

[0058]It is noted that the detent plate may be coupled to the spool valve
of the manual valve of automatic transmission 30 with a rod and the like
interposed therebetween. The shaft is rotated by actuator 42.

[0059]Although actuator 42 is described as a rotationally driven motor in
the present embodiment, actuator 42 is not particularly limited thereto,
but may be, for example, a linearly driven motor. In addition, actuator
42 is not particularly limited to a motor.

[0060]Output shaft sensor 44 detects the rotational position of a shaft
102. Specifically, output shaft sensor 44 is connected to SBW-ECU 50 and
transmits a signal (rotational position signal) indicating the rotation
angle of shaft 102 to SBW-ECU 50. SBW-ECU 50 detects the shift position
based on the received signal indicating the rotational position. A
predetermined range of an output value corresponding to each shift
position is set in a memory of SBW-ECU 50. SBW-ECU 50 determines the
currently selected shift position by determining which range
corresponding to each shift position the received signal indicating the
rotation angle of shaft 102 corresponds to. In addition, in the present
embodiment, it is assumed that a change in the output value of output
shaft sensor 44 has a linear relationship with respect to a change in the
rotational position (angle) of shaft 102. Output shaft sensor 44 is for
detecting the rotation angle of shaft 102 that is the physical amount
corresponding to the amount of actuation of actuator 42.

[0061]Engine 32 is an internal combustion engine and transfers an output
generated by combustion to an input shaft of automatic transmission 30.
The output of engine 32 is controlled by EFI-ECU 54.

[0062]Power switch 62 is for starting up or stopping engine 32. A signal
indicating an operation state that is accepted by power switch 62 from a
vehicle's occupant such as the driver is transmitted to power supply ECU
60. In response to the operation signal from power switch 62, power
supply ECU 60 turns off power supply relay 66 or transmits a signal for
requesting startup of engine 32 to EFI-ECU 54. When receiving the signal
for requesting startup of engine 32 from power supply ECU 60, EFI-ECU 54
starts up engine 32. Specifically, fuel injection control over a fuel
injection injector and ignition control over an ignition plug are
exercised, together with cranking by a starter (not shown).

[0063]Vehicle speed sensor 64 detects the physical amount corresponding to
the speed of the vehicle. For example, vehicle speed sensor 64 may detect
the rotation speed of the wheel, or may detect the rotation speed of the
output shaft of automatic transmission 30. Alternatively, vehicle speed
sensor 64 may directly detect the speed of the vehicle by using the GPS
(Global Positioning System) and the like.

[0064]In the present embodiment, vehicle speed sensor 64 is connected to
VSC-ECU 56, and transmits a signal indicating the detected speed of the
vehicle to VSC-ECU 56. VSC-ECU 56 transmits, to power supply ECU 60, the
signal indicating the speed of the vehicle that is received from vehicle
speed sensor 64.

[0065]It is noted that vehicle speed sensor 64 may be directly connected
to power supply ECU 60, or may be connected to at least any one of
SBW-ECU 50, ECT-ECU 52, EFI-ECU 54, and VSC-ECU 56.

[0066]In addition to the oil temperature, ECT-ECU 52 controls the shift
state of automatic transmission 30 based on the physical amount related
to the state of automatic transmission 30 (e.g., the rotation speed of a
turbine, the rotation speed of the output shaft and the rotation speed of
the engine).

[0067]In addition to the opening degree of an accelerator, EFI-ECU 54
controls the output of engine 32 based on the physical amount related to
the state of the engine (e.g., the water temperature, the amount of
intake air and the like).

[0068]In addition to the master cylinder pressure, VSC-ECU 56 controls the
brake hydraulic pressure in brake device 72 based on the physical amount
related to the behavior of the vehicle (e.g., wheel speed).

[0069]Meter 58 presents the state of the vehicle equipment, the state of
the shift position and the like. Meter 58 is provided with a display unit
(not shown) that displays an instruction, a warning and the like to the
driver issued by SBW-ECU 50 or power supply ECU 60.

[0070]Brake device 72 causes the wheel to produce the braking force by
using the negative pressure generated as a result of actuation of engine
32. For example, brake device 72 includes a brake pedal, a vacuum booster
coupled to the brake pedal, a master cylinder coupled to the vacuum
booster, a hydraulic circuit including a brake actuator and the like, and
a disc brake provided at the wheel.

[0071]If engine 32 is a gasoline engine, an intake pipe of engine 32 is
coupled to the vacuum booster. The operation force applied to the brake
pedal by the driver is boosted in the vacuum booster by using the
negative pressure generated at the intake pipe when engine 32 is
actuated, and is transferred to the master cylinder.

[0072]If engine 32 is a diesel engine, the vacuum booster is coupled to
the vacuum pump actuated by the motive power of engine 32. The operation
force applied to the brake pedal by the driver is boosted in the vacuum
booster by using the negative pressure generated at the negative pressure
pump when engine 32 is actuated, and is transferred to the master
cylinder.

[0073]When the operation signal received from power switch 62 is a signal
corresponding to an instruction to start up engine 32, power supply ECU
60 transmits a relay drive signal to power supply relay 66 to turn on IG
relay 68 and ACC relay 70, and in addition, transmits the signal for
requesting startup of engine 32 to EFI-ECU 54.

[0074]In addition, when the operation signal received from power switch 62
is a signal corresponding to an instruction to stop engine 32, power
supply ECU 60 transmits the relay drive signal to power supply relay 66
to turn off at least IG relay 68. It is noted that power supply ECU 60
may drive power supply relay 66 based on the operation state of the brake
pedal and/or the operation state of the shift lever, in addition to the
operation signal from power switch 62.

[0075]In response to the relay drive signal from power supply ECU 66,
power supply relay 66 turns on only ACC relay 70, turns on IG relay 68
after turning on ACC relay 70, turns off only IG relay 68, or turns off
ACC relay 70 after turning off IG relay 68. When IG relay 68 is turned
on, electric power is supplied to the vehicle-mounted equipment actuated
at least in association with startup of engine 32.

[0076]Power supply ECU 60 transmits the relay drive signal corresponding
to on and off combinations of IG relay 68 and ACC relay 70 to power
supply relay 66, in accordance with the actuation state of the engine and
the operation state of power switch 62.

[0077]The operation state of power switch 62 is a state based on a time
period during which the operation of power switch 62 continues.
Specifically, the operation state is a state based on a time period
during which a button serving as an input portion of power switch 62 is
pressed.

[0078]FIG. 2 illustrates a configuration of shift switching mechanism 48.
Although the shift position is described hereinafter as the one that
means the P position and the non-P position and that does not include
each of the R, N and D positions in the non-P position, the shift
position may include each of the R, N and D positions. In other words,
although a configuration of the two positions, that is, the P position
and the non-P position is described in the present embodiment, the
present invention may have a configuration of the four positions, that
is, the P position and the non-P position including each of the R, N and
D positions.

[0079]Shift switching mechanism 48 includes shaft 102 rotated by actuator
42, a detent plate 100 rotated with the rotation of shaft 102, a rod 104
operated with the rotation of detent plate 100, a parking lock gear 108
fixed to the not-shown output shaft of automatic transmission 30, a
parking lock pole 106 for locking parking lock gear 108, a detent spring
110 for limiting the rotation of detent plate 100 and fixing the shift
position, and a roller 112. Detent plate 100 is driven by actuator 42 and
switches the shift position. In addition, encoder 46 functions as
counting means for obtaining a count corresponding to the amount of
rotation of actuator 42. Furthermore, output shaft sensor 44 detects the
rotational position of shaft 102.

[0080]FIG. 2 illustrates the state in which the shift position is in the
non-P position. In this state, parking lock pole 106 does not lock
parking lock gear 108, and thus, the rotation of the drive shaft of the
vehicle is not limited. If shaft 102 is turned clockwise from this state
by actuator 42, rod 104 is pushed by detent plate 100 in the direction of
an arrow A shown in FIG. 2, and parking lock pole 106 is pushed up by a
tapered parking lock cam 210 provided at the tip of rod 104, in the
direction of an arrow B shown in FIG. 2. With the rotation of detent
plate 100, roller 112 of detent spring 110 situated in one of the two
troughs provided at the top of detent plate 100, that is, in a location
120 of the non-P position, climbs over a crest 122 and moves to the other
trough, that is, to a location 124 of the P position. Roller 112 is
provided at detent spring 110 to be capable of rotating in the axial
direction of roller 112. When detent plate 100 rotates until roller 112
reaches location 124 of the P position, parking lock pole 106 is pushed
up to the location where a protrusion 208 of parking lock pole 106 meshes
with a region between the gear teeth of parking lock gear 108. As a
result, the rotation of the drive shaft of the vehicle is mechanically
limited and the shift position is switched to the P position.

[0081]In shift control system 10 according to the present embodiment, in
order to reduce the load applied to the components of shift switching
mechanism 48 such as detent plate 100, detent spring 110 and shaft 102 at
the time of switching the shift position, SBW-ECU 50 controls the amount
of rotation of actuator 42 to lessen the impact when roller 112 of detent
spring 110 climbs over crest 122 and falls.

[0082]A plane located on the side distant from crest 122 in each trough of
detent plate 100 is referred to as a wall. In other words, the wall is in
the location where roller 112 hits the wall when roller 112 of detent
spring 110 climbs over crest 122 and falls to the trough without control
by SBW-ECU 50 that will be described hereinafter. The wall in location
124 of the P position is referred to as a P wall 162, and the wall in
location 120 of the non-P position is referred to as a non-P wall 160.

[0083]Although a configuration in which a parking lock mechanism 200 is
provided within automatic transmission 30 is described in the present
embodiment, parking lock mechanism 200 may be provided in any location if
parking lock mechanism 200 is provided at the rotation shaft between the
driving wheel and automatic transmission 30.

[0084]Parking lock mechanism 200 includes parking lock gear 108 and
parking lock pole 106 as shown in FIG. 3. In the present embodiment,
parking lock gear 108 may be provided at the output shaft of automatic
transmission 30, or may be provided at a shaft of the gear engaged with
the output shaft. Parking lock gear 108 has a disc shape and is provided
with a plurality of gear teeth 204 along the direction of rotation of a
shaft 212.

[0085]Parking lock pole 106 is supported by a case of automatic
transmission 30 such that one end thereof can be freely rotated.
Protrusion 208 meshing with gear teeth 204 of parking lock gear 108 is
provided in the center of parking lock pole 106. At the other end of
parking lock pole 106, parking lock cam 210 is provided to abut parking
lock pole 106. Parking lock cam 210 has, for example, a conical shape and
when parking lock cam 210 moves from the back side to the front side of
the sheet in FIG. 3, the other end of parking lock pole 106 rotationally
moves in the direction of an arrow in

[0086]FIG. 3 along a sloped portion of the conical shape. In accordance
with the movement of the shift lever (not shown) to the location
corresponding to the P position, parking lock cam 210 moves from the back
side to the front side of the sheet in FIG. 3. At this time, parking lock
cam 210 is actuated by the rotation of detent plate 100 caused by driving
of actuator 42. When protrusion 208 of parking lock pole 106 moves, as a
result of driving of parking lock cam 210, to the predetermined location
where protrusion 208 meshes with gear teeth 204 of parking lock gear 108,
the rotation of parking lock gear 108 is limited. Parking lock mechanism
200 is actuated in such a manner, thereby limiting the rotation of the
driving wheel.

[0087]In the configuration of the vehicle as described above, power supply
ECU 60 serving as the control device for the vehicle according to the
present embodiment has the following feature. When receiving the
instruction to stop engine 32, power supply ECU 60 determines whether or
not the rotation of parking lock gear 108 is limited, based on the
physical amount related to the actuation state of parking lock mechanism
200. When determining that the rotation of parking lock gear 108 is not
limited, power supply ECU 60 maintains engine 32 in the actuated state.
When determining that the rotation of parking lock gear 108 is limited,
power supply ECU 60 stops engine 32.

[0088]Specifically, when the speed of the vehicle received from vehicle
speed sensor 64 via VSC-ECU 56 is higher than or equal to predetermined
speed α, power supply ECU 60 determines that the rotation of
parking lock gear 108 is not limited. When determining that the rotation
of parking lock gear 108 is not limited, power supply ECU 60 maintains IG
relay 68 in the ON state, thereby maintaining engine 32 in the actuated
state.

[0089]It is noted that, when engine 32 is at a standstill, power supply
ECU 60 may turn on both IG relay 68 and ACC relay 70 and transmit the
signal for requesting startup of engine 32 to EFI-ECU 54.

[0090]Furthermore, when determining that the rotation of parking lock gear
108 is not limited, power supply ECU 60 transmits a warning signal to
meter 58 to notify the vehicle's occupant that engine 32 is maintained in
the actuated state. In meter 58, a warning lamp corresponding to the
received warning signal lights up to notify the vehicle's occupant that
engine 32 is maintained in the actuated state.

[0092]FIG. 4 shows a functional block diagram of power supply ECU 60 and
SBW-ECU 50. Power supply ECU 60 includes an input interface (that will be
described as an input I/F hereinafter) 300, a processing unit 350, a
communicating unit 400, a storage unit 450, and an output interface (that
will be described as an output I/F hereinafter) 500.

[0093]Input I/F 300 receives the operation signal from power switch 62 and
a vehicle speed signal from VSC-ECU 56, and transmits the signals to
processing unit 350.

[0096]Operation determining unit 352 determines whether the operation
state of power switch 62 is the operation state corresponding to the
instruction to stop engine 32, or the operation state corresponding to
the instruction to forcibly stop engine 32, based on the operation signal
received via input I/F 300.

[0097]It is noted that operation determining unit 352 does not determine
only the above operation states. In addition to the above operation
states, operation determining unit 352 may determine whether the
operation state of power switch 62 is the operation state corresponding
to the instruction to start up engine 32, or the operation state
corresponding to an instruction to effect a transition to the power
supply position of an accessory (ACC). Furthermore, in addition to the
operation state of power switch 62, operation determining unit 352 may
determine the presence or absence of the instruction from the driver
based on the location of the brake pedal and/or the shift lever.

[0098]Operation determining unit 352 uses a timer to measure a time period
that has elapsed since the operation signal indicating that the button of
the input portion of power switch 62 was pressed was received. When the
measured elapsed time period, that is, the time period during which the
button is pressed is longer than or equal to a predetermined time period
(1) and within a predetermined time period (2), operation determining
unit 352 determines that the operation state of power switch 62 is the
operation state corresponding to the instruction to stop engine 32.
Predetermined time period (2) is longer than predetermined time period
(1).

[0099]Furthermore, when the time period during which the button is pressed
is longer than a predetermined time period (3), operation determining
unit 352 determines that the operation state of power switch 62 is the
operation state corresponding to the instruction to forcibly stop engine
32. Predetermined time period (3) is at least longer than or equal to
predetermined time period (2).

[0100]It is noted that operation determining unit 352 may turn on a stop
instruction determination flag when the operation state of power switch
62 is the operation state corresponding to the instruction to stop engine
32, and may turn on a forced stop instruction determination flag when the
operation state of power switch 62 is the operation state corresponding
to the instruction to forcibly stop engine 32.

[0101]Vehicle speed determining unit 354 determines whether or not a speed
V of the vehicle is lower than predetermined speed α, based on the
vehicle speed signal. Predetermined speed α is not particularly
limited if predetermined speed α is the speed of the vehicle at
which it can be determined that the vehicle is substantially at a
standstill. For example, predetermined speed α is 4 km per hour. It
is noted that, when determining that speed V of the vehicle is lower than
predetermined speed α, vehicle speed determining unit 354 may turn
on a vehicle stop determination flag.

[0102]When the operation state of power switch 62 is the operation state
corresponding to the instruction to stop engine 32 and speed V of the
vehicle is lower than predetermined speed α, auto-P request
transmitting unit 356 transmits the auto-P request signal indicating a
request to exercise auto-P control, to SBW-ECU 50 via communicating unit
400 and communication line 402. It is noted that, in the present
embodiment, "auto-P control" refers to control in which the stop control
of engine 32 and the drive control of the actuator for changing the shift
position to the P position are simultaneously exercised.

[0103]Timer unit 358 measures a time period that has elapsed since the
auto-P request signal was transmitted. It is noted that timer unit 358
may only measure a time period that has elapsed from the point in time at
the earliest when the operation state of power switch 62 was determined
as the operation state corresponding to the instruction to stop engine
32.

[0104]Stop condition determining unit 360 determines whether or not the
condition for stopping engine 32 is satisfied. The condition for stopping
engine 32 includes the condition that the elapsed time period measured by
timer unit 358 becomes longer than or equal to a predetermined time
period T and the condition that the P position signal and the auto-P
completion signal are received from SBW-ECU 50. When the condition for
stopping engine 32 is satisfied, for example, stop condition determining
unit 360 may turn on a stop condition satisfaction flag.

[0106]In addition, when the operation state of power switch 62 is
determined as the operation state corresponding to the instruction to
forcibly stop engine 32, relay driving unit 362 transmits the relay drive
signal to power supply relay 66 via output I/F 500 to turn off IG relay
68 and maintain ACC relay 70 in the ON state. When the forced stop
instruction determination flag is ON, for example, relay driving unit 362
may drive power supply relay 66 to turn off IG relay 68 and maintain ACC
relay 70 in the ON state.

[0107]Furthermore, when speed V of the vehicle is lower than predetermined
speed α and the position signal is not the P position signal after
predetermined time period T or longer has elapsed since the auto-P
request signal was transmitted, relay driving unit 362 transmits the
relay drive signal to power supply relay 66 via output I/F 500 to turn
off IG relay 68 and maintain ACC relay 70 in the ON state.

[0108]It is noted that, when the vehicle speed determination flag is ON
and the position signal is not the P position signal after predetermined
time period T or longer has elapsed since the auto-P request signal was
transmitted, for example, relay driving unit 362 may drive power supply
relay 66 to turn off IG relay 68 and maintain ACC relay 70 in the ON
state.

[0109]In addition, when the operation state of power switch 62 does not
correspond to any of the instruction to stop engine 32 and the
instruction to forcibly stop engine 32, or when speed V of the vehicle is
higher than or equal to predetermined speed α, relay driving unit
362 maintains IG relay 68 and ACC relay 70 in the ON state. It is noted
that, when the vehicle speed determination flag, the stop instruction
determination flag and the forced stop instruction determination flag are
all OFF, for example, relay driving unit 362 may drive power supply relay
66 to maintain IG relay 68 and ACC relay 70 in the ON state.

[0110]Although, in the present embodiment, operation determining unit 352,
vehicle speed determining unit 354, auto-P request transmitting unit 356,
timer unit 358, stop condition determining unit 360, and relay driving
unit 362 are all described as those functioning as software that are
implemented by a CPU (Central Processing Unit), which is processing unit
350, executing a program stored in storage unit 450, they may be
implemented by hardware. It is noted that such program is stored in a
recording medium and mounted on the vehicle.

[0111]Various information, a program, a threshold value, a map and the
like are stored in storage unit 450, and read from processing unit 350 as
required.

[0115]Request determining unit 602 determines the presence or absence of
the request to exercise the auto-P control. When communicating unit 650
receives the auto-P request signal from power supply ECU 60 via
communication line 402, request determining unit 602 determines that the
request to exercise the auto-P control is present. It is noted that, when
determining that the request to exercise the auto-P control is present,
for example, request determining unit 602 may turn on an exercise request
determination flag.

[0116]When the request to exercise the auto-P control is present, actuator
driving unit 604 drives actuator 42 such that the shift position is
switched to the P position, that is, roller 112 moves to location 124 of
the P position based on the count signal and the rotational position
signal. Specifically, actuator driving unit 604 generates an actuator
drive control signal based on the count signal and the rotational
position signal, and transmits the actuator drive control signal to
actuator 42 via output I/F 750. It is noted that, when the exercise
request determination flag is turned on, for example, actuator driving
unit 604 may drive actuator 42 such that the shift position is switched
to the P position.

[0117]When roller 112 moves to location 124 of the P position, position
signal updating unit 606 updates the position signal to be transmitted to
power supply ECU 60, from the non-P position signal to the P position
signal.

[0118]Vehicle speed determining unit 608 determines whether or not speed V
of the vehicle is lower than predetermined speed α. Vehicle speed
determining unit 608 determines whether or not speed V of the vehicle is
lower than predetermined speed α, based on the vehicle speed signal
received from power supply ECU 60 or VSC-ECU 56 via communication line
402. It is noted that vehicle speed sensor 64 is connected to input I/F
550 and vehicle speed determining unit 608 may receive the vehicle speed
signal via input I/F 550. In addition, when determining that speed V of
the vehicle is lower than predetermined speed α, for example,
vehicle speed determining unit 608 may turn on the vehicle speed
determination flag. Although a configuration is described in the present
embodiment in which it is determined in SBW-ECU 50 whether or not speed V
of the vehicle is lower than predetermined speed α, SBW-ECU 50 may
receive, from power supply ECU 60, the result of the determination as to
whether or not speed V of the vehicle is lower than predetermined speed
α, for example.

[0119]When it is determined that the position signal is the P position
signal and speed V of the vehicle is lower than predetermined speed
α, completion/non-completion signal transmitting unit 610 transmits
the auto-P completion signal to power supply ECU 60 via communicating
unit 650 and communication line 402.

[0120]In addition, when the position signal is the non-P position signal
or when speed V of the vehicle is higher than or equal to predetermined
speed α, completion/non-completion signal transmitting unit 610
transmits the auto-P non-completion signal to power supply ECU 60.

[0121]It is noted that completion/non-completion signal transmitting unit
610 may transmit the auto-P completion signal to power supply ECU 60 when
the position signal is the P position signal and the vehicle speed
determination flag is ON, and may transmit the auto-P non-completion
signal to power supply ECU 60 when the position signal is the non-P
position signal or when the vehicle speed determination flag is OFF, for
example.

[0122]Although, in the present embodiment, request determining unit 602,
actuator driving unit 604, position signal updating unit 606, vehicle
speed determining unit 608, and completion/non-completion signal
transmitting unit 610 are all described as those functioning as software
that are implemented by a CPU, which is processing unit 600, executing a
program stored in storage unit 700, they may be implemented by hardware.
It is noted that such program is stored in a recording medium and mounted
on the vehicle.

[0123]Various information, a program, a threshold value, a map and the
like are stored in storage unit 700, and read from processing unit 600 as
required.

[0124]Although power supply ECU 60 and SBW-ECU 50 are described in the
present embodiment as those configured by two electronic control units
connected to allow bidirectional communication, power supply ECU 60 and
SBW-ECU 50 may be configured by an integrated electronic control unit. In
the present embodiment, power supply ECU 60 and SBW-ECU 50 simultaneously
execute the programs stored in respective storage units 450 and 700.

[0125]A control structure of the program running on power supply ECU 60
serving as the control device for the vehicle according to the present
embodiment will be described hereinafter with reference to FIG. 5.

[0126]In step (that will be described as "S" hereinafter) 100, power
supply ECU 60 determines whether or not power switch 62 is in the short
pressed state. "Short press" corresponds to the operation state in which
the time period during which the button serving as the input portion of
power switch 62 is pressed is longer than predetermined time period (1)
and shorter than predetermined time period (2). If power switch 62 is in
the short pressed state (YES in S100), the process is moved to S102. If
not (NO in S100), the process is moved to S114.

[0127]In S102, power supply ECU 60 determines whether or not speed V of
the vehicle is lower than predetermined speed α. If speed V of the
vehicle is lower than predetermined speed α (YES in S102), the
process is moved to S104. If not (NO in S102), the process is moved to
S122.

[0128]In S104, power supply ECU 60 transmits the auto-P request signal to
SBW-ECU 50. In S106, power supply ECU 60 starts the timer. In S108, power
supply ECU 60 determines whether or not the time period measured by the
timer becomes longer than or equal to predetermined time period T. If
predetermined time period T has elapsed (YES in S108), the process is
moved to S116. If not (NO in S108), the process is moved to S110.

[0129]In S110, power supply ECU 60 determines whether or not to receive
the P position signal and the auto-P completion signal from SBW-ECU 50.
If the P position signal and the auto-P completion signal are received
(YES in S110), the process is moved to S112. If not (NO in S110), the
process is returned to S108.

[0131]In S114, power supply ECU 60 determines whether or not power switch
62 is in the long pressed state. "Long press" corresponds to the
operation state in which the time period during which the button serving
as the input portion of power switch 62 is pressed is longer than or
equal to predetermined time period (3). If power switch 62 is in the long
pressed state (YES in S114), the process is moved to S124. If not (NO in
S114), the process is moved to S122.

[0132]In S116, power supply ECU 60 determines whether or not speed V of
the vehicle is lower than predetermined speed α. If speed V of the
vehicle is lower than predetermined speed α (YES in S116), the
process is moved to S118. If not (NO in S116), the process is moved to
S122.

[0133]In S118, power supply ECU 60 determines whether or not to receive
the P position signal from SBW-ECU 50. If the P position signal is
received (YES in S118), the process is moved to S112. If not (NO in
S118), the process is moved to S120.

[0134]In S120, power supply ECU 60 drives power supply relay 66 to turn
off IG relay 68 and maintain ACC relay 70 in the ON state.

[0135]In S122, power supply ECU 60 drives power supply relay 66 to
maintain both IG relay 68 and AC relay 70 in the ON state.

[0137]Next, a control structure of the program running on SBW-ECU 50 will
be described with reference to FIG. 6.

[0138]In S200, SBW-ECU 50 determines whether or not to receive the auto-P
request signal from power supply ECU 60. If the auto-P request signal is
received (YES in S200), the process is moved to S202. If not (NO in
S200), the process is returned to S200.

[0139]In S202, if the shift position is in the non-P position (e.g., if
the position signal to be transmitted to power supply ECU 60 is the non-P
position signal), SBW-ECU 50 drives actuator 42 such that roller 112
moves to the location of the P position. In S204, SBW-ECU 50 updates the
position signal to be transmitted to power supply ECU 60, from the non-P
position signal to the P position signal.

[0140]In S206, SBW-ECU 50 determines whether or not speed V of the vehicle
is lower than predetermined speed α. If speed V of the vehicle is
lower than predetermined speed α (YES in S206), the process is
moved to S208. If not (NO in S206), the process is moved to S210.

[0142]The operation of power supply ECU 60 and SBW-ECU 50 based on the
above structures and flowcharts will be described.

[0143]It is assumed, for example, that the driver brings the vehicle to
stop by operating the brake and the like while the vehicle is traveling
on an inclined road surface (e.g., uphill road).

[0144]If the driver presses power switch 62 for a short time period to
stop engine 32 (YES in S100), and if speed V of the vehicle is lower than
predetermined speed α (YES in S102), the auto-P request signal is
transmitted to SBW-ECU 50 (S104). Thereafter, the timer starts (S106).

[0145]If SBW-ECU 50 receives the auto-P request signal (YES in S200),
actuator 42 is driven (S202). When the shift position is switched from
the non-P position to the P position, the position signal is updated from
the non-P position signal to the P position signal (S204).

[0146]<When Engine is Maintained in Actuated State>

[0147]When the driver presses power switch 62 for a short time period and
eases press-down of the brake pedal, the braking force that acts on the
vehicle by brake device 72 is lowered, and thus, the vehicle starts to
move on the inclined road surface in the downward direction due to
gravity before actuation of parking lock mechanism 200 is completed.
Therefore, if speed V of the vehicle becomes higher than or equal to
predetermined speed α (YES in S206), actuation of parking lock
mechanism 200 cannot be completed and the auto-P non-completion signal is
transmitted from SBW-ECU 50 to power supply ECU 60 (S210).

[0148]The P position signal and the auto-P completion signal are not
received (NO in S110) until the time period measured by the timer becomes
longer than or equal to predetermined time period T (NO in S108).
Therefore, if predetermined time period T has elapsed (YES in S108), it
is determined whether or not speed V of the vehicle is lower than
predetermined speed α (S116).

[0149]If speed V of the vehicle increases to become higher than or equal
to predetermined speed α with the press-down of the brake pedal
eased (NO in S116), power supply relay 66 is driven to maintain both IG
relay 68 and ACC relay 70 in the ON state (S122). Therefore, engine 32 is
maintained in the actuated state. Since the pressure in the vacuum
booster is maintained at the negative pressure by maintaining engine 32
in the actuated state, degradation in brake performance in brake device
72 is suppressed.

When Actuation of Engine is Stopped (Example 1)

[0150]When the driver presses power switch 62 for a short time period and
eases press-down of the brake pedal, the braking force that acts on the
vehicle by brake device 72 is lowered, and thus, the vehicle starts to
move on the inclined road surface in the downward direction due to
gravity before actuation of parking lock mechanism 200 is completed.
Therefore, if speed V of the vehicle becomes higher than or equal to
predetermined speed α (YES in S206), actuation of parking lock
mechanism 200 cannot be completed and the auto-P non-completion signal is
transmitted from SBW-ECU 50 to power supply ECU 60 (S210).

[0151]The P position signal and the auto-P completion signal are not
received (NO in S110) until the time period measured by the timer becomes
longer than or equal to predetermined time period T (NO in S108).
Therefore, if predetermined time period T has elapsed (YES in S108), it
is determined whether or not speed V of the vehicle is lower than
predetermined speed α (S116).

[0152]If speed V of the vehicle falls below predetermined speed α
(YES in S116) by the driver's press-down of the brake pedal to increase
the braking force that acts on the vehicle, before predetermined time
period T has elapsed, it is determined whether or not to receive the P
position signal.

[0153]When switching to the P position is completed, the position signal
is updated from the non-P position to the P position. If power supply ECU
60 receives the P position signal (YES in S118), power supply relay 66 is
driven to turn off IG relay 68 and ACC relay 70 (S112). At this time,
actuation of engine 32 stops.

[0154]When switching to the P position is not completed, the position
signal remains at the non-P position. If power supply ECU 60 does not
receive the P position signal (NO in S118), power supply relay 66 is
driven to turn off IG relay 68 and maintain ACC relay 70 in the ON state
(S120). At this time, actuation of engine 32 stops. The location of the
vehicle is fixed as a result of actuation of parking lock mechanism 200.

When Actuation of Engine is Stopped (Example 2)

[0155]When the driver presses power switch 62 for a short time period and
retains press-down of the brake pedal, the braking force that acts on the
vehicle by brake device 72 is retained. At this time, if speed V of the
vehicle is lower than predetermined speed α (YES in S206), parking
lock mechanism 200 is actuated with the location of the vehicle fixed. It
is determined that the location of the vehicle is in the fixed state, and
the auto-P completion signal is transmitted from SBW-ECU 50 to power
supply ECU 60 (S208).

[0156]If the P position signal and the auto-P completion signal are
received (YES in S110) before the time period measured by the timer
becomes longer than or equal to predetermined time period T (NO in S108),
power supply relay 66 is driven to turn off IG relay 68 and ACC relay 70
(S112). Therefore, actuation of engine 32 stops. The location of the
vehicle is fixed as a result of actuation of parking lock mechanism 200.

When Actuation of Engine is Stopped (Example 3)

[0157]If the driver presses power switch 62 for a long time period (NO in
S100, YES in S114), the emergency stop process is performed (S124). In
other words, power supply relay 66 is driven to turn off IG relay 68 and
maintain ACC relay 70 in the ON state (S124). At this time, actuation of
engine 32 stops.

[0158]As described above, in the control device for the vehicle according
to the present embodiment, even when the instruction to stop the engine
is received, the engine is maintained in the actuated state if it is
determined that the rotation of the parking lock gear is not limited.
This allows suppression of engine stop before actuation of the parking
lock mechanism is completed. Therefore, degradation in brake performance
due to the engine stop can be suppressed. For example, even when the
vehicle moves during parking of the vehicle on a road surface having an
inclination and during actuation of the parking lock mechanism after the
instruction to stop the engine is received as a result of short press of
power switch 62, the location of the vehicle can be fixed by the driver's
operation of the brake, to suppress the movement of the vehicle which is
not intended by the driver. In addition, when actuation of the parking
lock mechanism is completed, the movement of the vehicle can be adapted
to the driver's intention by stopping the engine. Accordingly, there can
be provided a control device for a vehicle and a method for controlling a
vehicle that suppress the movement of the vehicle contrary to the
driver's intention.

[0159]In addition, when the engine is at a standstill, degradation in
performance of the brake using the negative pressure based on actuation
of the engine can be suppressed by starting up the engine again.

[0160]It is noted that, when receiving the auto-P non-completion signal,
the power supply ECU may provide a display for notifying the vehicle's
occupant that the engine is maintained in the actuated state. It is noted
that notification may be provided by an information transfer medium such
as a sound, an image or a character. In addition to this, notification
may also be provided by displaying information that encourages the driver
to press down the brake pedal.

[0161]Although a configuration is described in the present embodiment in
which it is determined whether or not the rotation of parking lock gear
108 is limited, based on speed V of the vehicle, the present invention is
not particularly limited to the determination based on the speed of the
vehicle.

[0162]For example, it may be determined whether or not the rotation of
parking lock gear 108 is limited, by determining whether protrusion 208
of parking pole 106 meshes with the gear teeth of parking lock gear 108
or protrusion 208 of parking pole 106 does not mesh with the gear teeth
of parking lock gear 108, based on an output signal from an angle sensor
74 provided at parking pole 106.

[0163]Alternatively, a voltmeter 76 and the like is used to detect
electric power of a power supply 78 (e.g., a power storage mechanism such
as a battery) that supplies electric power to actuator 42, and power
supply ECU 60 may determine that the rotation of parking lock gear 108 is
not limited, if the detected electric power is not electric power that
allows driving of actuator 42.

[0164]It should be understood that the embodiments disclosed herein are
illustrative and not limitative in any respect. The scope of the present
invention is defined by the terms of the claims, rather than the above
description, and is intended to include any modifications within the
scope and meaning equivalent to the terms of the claims.